The invention relates to an electrosurgical apparatus, comprising an HF generator and an HF instrument.
An apparatus of the type mentioned at the beginning is used in what is termed electrosurgery. High-frequency currents generated by the HF generator are led into the body of a patient via the HF instrument connected to the HF generator, particularly in the course of minimally invasive surgery, in order to use the HF instrument at an operating site to coagulate and/or to cut tissue under the action of the high-frequency currents. During the coagulation, vessels are obliterated in order to cause hemostatis upon removal of tissue. The coagulation and the cutting by means of high-frequency current differ from one another with regard to the applied power of the high-frequency current and, if appropriate, with regard to the duration of the application. In the coagulation mode of an electrosurgical apparatus, work is performed as a rule with relatively low HF powers and intermittently, whereas higher HF powers are required to cut tissue by means of high-frequency current, in order to generate the electric arc required for cutting tissue by means of high-frequency current. Furthermore, work is also not performed intermittently during cutting, but continuously.
In accordance with these two previously described operating modes of coagulation and cutting, the HF generator of such an electrosurgical apparatus is capable of providing high-frequency currents with the corresponding powers required for coagulation and cutting.
When working with an HF instrument, however, the operating modes of “coagulation” and “cutting” are, as a rule, not required simultaneously, but alternately, that is to say the work steps of cutting and coagulation take place one after another and alternately, but not simultaneously. The HF generator can be activated correspondingly with the aid of the operating modes of “coagulation” and “cutting”.
So that the surgeon operating the HF instrument need not undertake the activation of the operating modes at the HF generator situated away from the operating table and in the non-sterile area of the operating room, or need not appropriately instruct an assistant to switch over between the operating modes, the HF instrument itself is provided with a possibility for activating the operating modes in the form of two switches that can be operated with the fingers.
For example, the first switch is assigned the operating mode of “coagulation” and the second switch is assigned the operating mode of “cutting”. Consequently, there correspond in each case to the first switch and the second switch a first operating state, for example a relatively high output power of the HF generator, or a second operating state, for example lower output power with a possibly intermittent operation.
The first switch and the second switch are connected to at least one control signal line, which is connected to the main line of the HF instrument via which the active electrode at the distal end of the HF instrument is fed. In addition to the high-frequency current, the main line feeds in a control input signal from which, depending on which of the two switches is actuated, a corresponding control output signal for activating the operating state assigned to the actuated switch is generated with the aid of the signal coding means, which control output signal is fed to the HF generator via that control signal line to which the respective switch is connected, in order to activate the corresponding operating state of the HF generator.
In an apparatus disclosed in DE 30 45 996 A1, in addition to the previously mentioned two switches for switching over between the operating modes of “coagulation” and “cutting”, still further switches are provided on the HF instrument, specifically for respectively increasing or lowering the output power in the operating mode respectively selected. Additional signal lines are required in the case of this known apparatus in order to implement the further functions for switching over the HF generator.
An apparatus comparable thereto is disclosed in EP 0 186 369 A1 and likewise has four switches for switching over between the operating modes of “coagulation” and “cutting”, as well as for increasing or lowering the output power in each of the two operating modes. Three signal lines are required overall for the four switches in the case of this known apparatus.